Patent Literature 1 discloses an observation device (ophthalmic imaging device) which scans an eye of an examinee with a laser beam irradiation position and receives a reflected beam from the eye by a light detection unit, thereby observing the eye. In the observation device disclosed in this literature, the reflected beam from the eye is split into two by a half mirror, one of the split beams is received by the light detection unit, where its power is detected, and the other is received by a wavefront detection unit, where its wavefront aberration is detected. A wavefront modulation unit (wavefront compensation unit) compensates for the wavefront aberration of the reflected beam according to the wavefront aberration detected by the wavefront detection unit, and an image of the eye is obtained according to the light power detected by the light detection unit. The observation device disclosed in the literature is said to be able to obtain a photographed image having a high resolution by the foregoing.
In general, wavefront aberration compensation techniques including wavefront detection and wavefront modulation as mentioned above can improve image-forming characteristics and measurement accuracy. Conventionally, the wavefront aberration compensation techniques have mainly been used for astronomical telescopes. Recently, however, the wavefront aberration compensation techniques have also been coming into use for fundus cameras, scanning laser ophthalmoscopes (SLO), optical coherent tomography (OCT), laser microscopes, and the like.
Imaging using such a wavefront aberration compensation technique enables observation with a high resolution which has not conventionally been achievable. When its subject is a fundus of an eye in particular, photoreceptor cells and minute blood vessels can be observed. Observing the photoreceptor cells is useful for diagnosing age-related eye diseases. Observing the minute blood vessels is useful for early diagnosis of circulatory diseases. Therefore, a fundus imaging system using a wavefront aberration compensation technique, if commercialized, is expected to make a great impact on medical industries.    Patent Literature 1: Japanese Patent Application Laid-Open No. 2007-014569